Adds support for numpy number and dtype in _to/_fromdict

Supports numpy.number and numpy.dtype objects when running the _todict and _fromdict functions of Dictable
Merge pull request #78 from blazetopher/np_tofromdict

Adds support for numpy number and dtype in _to/_fromdict
Fixes bug with default fill_value

Addresses issue where default float fill values are set as numpy.number objects rather than builtin types - can cause issues downstream when serializing to JSON
Merge pull request #79 from blazetopher/fix_fillval_bug

Fixes bug with default fill_value
Adds 'inner_encoding' to ArrayType

Adds 'inner_encoding' attribute to ArrayType parameter type.  The attribute enables outbound (retrieval) conversion of the stored object-array into an ndarray who's datatype is indicated by inner_encoding.  Object and String data types are not converted.  If inner_encoding is None, the array is NOT converted,  this is the default.

Verified only for single-nested arrays (i.e. result in a 2d array).

Adds ArrayType with inner_encoding to Parameter Value Interop tests